This application is related to Japanese Patent Application No. 2000-208716 filed in Jul. 10, 2000, whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
This invention relates to a data communication system utilizing a cellular phone. More specifically, this invention relates to a data communication system utilizing a cellular phone allowed for delivering data such as advertisement by transmitting data to the cellular phone using error frames, and displaying messages such as characters on a liquid crystal screen of the body of the cellular phone.
2. Description of the Related Art
In a data communication system using a cellular phone (PDC (personal digital cellular) system of digital cellular phone) and in the PIAFS of PHS (PHS internet access forum standard), reliability in data communications has been enhanced by controlling error in the ARQ (automatic repeat request) system. That is, the data is divided into frames, and is exchanged by attaching a CRC code for correcting error to every frame. When an error is detected by a CRC code, the receiving side requests the transmission again, and a frame in which error has occurred is transmitted again to correct the error thereby to realize the data communication without become garbled of data.
Owing to these technologies compounded by the widespread proliferation of cellular data equipment such as modern cellular phones, mini-notebook personal computers and PDAs (personal digital assistant), the internet is becoming more easily accessible through the use of cellular data equipment by utilizing the data communication function of the cellular phone.
A method of delivering data such as advertisement by utilizing data communication through the cellular phone has been taught in, for example, Japanese Patent Laid-Open No. 340064/1998. According to this prior art, a large display device equipped with a cellular phone is installed on the rooftop of a building in an attempt to display chiefly advertisement, and picture signals are transmitted to the cellular phone through a wireless circuit in order to change or control the content displayed on the display device from a remote site (this is hereinafter referred to as first prior art).
According to technology disclosed in Japanese Patent Laid-Open No. 3072/1999, there is utilized a waiting time (e.g., a time of authentication in making a connection to the server of an internet service provider and a time for transferring data until a page www is read in) that occurs in making an access to a page www (world wide web) of the internet using high speed communications service such as the PlAFS of PHS, in order to display advertisement data down-loaded in advance from the advertisement data server during the waiting time (this is hereinafter referred to as second prior art).
The first prior art is suited for displaying advertisement like a signboard for a indefinite number of persons, but is not suited for delivering data such as advertisement for individual persons who own cellular phones. When the first prior art is applied to individual persons, the data must be sent from the delivery side by calling the individual""s cellular phones. In case the data are sent to the cellular phones that do not meet the system, it is not possible on the side of the cellular phone to make a distinction from the normal call, and it is expected that inconvenience may occur.
According to the second prior art, it is necessary to use a special tag for specifying the reading of advertisement on a page www. This cannot guarantee the operation in a browser which does not meet the special tag. When access is made by using an ordinary personal computer to a page that uses this special tag, therefore, it is likely to cause malfunction.
Further, the advertisement data are down-loaded while other data are not being communicated. Depending upon the cases, therefore, there may exist no timing for down-loading the advertisement data, and the advertisement may not often be displayed. Further, since the advertisement is displayed during the waiting time produced during the communication, the advertisement data are not often displayed when there is produced no waiting time even though the data may have been down-loaded from the advertisement data server. This is a serious problem from the standpoint of an advertisement medium. That is, even though the data may have been down-loaded from the advertisement data server, there is no guarantee whether the data are displayed on the client side, which may arouse a problem in collecting the advertisement fees.
This invention provides a data communication system utilizing a cellular phone, comprising a radio base station, a cellular phone having a function connecting to a network through radio communications with the radio base station to make data communications accompanied by error control using a CRC code, and a terminal connecting to the network by using the data communication function of the cellular phone to make data communications, wherein, when a message frame which is an error frame having a different CRC code portion is received from the radio base station, the cellular phone takes out and stores the data contained in the message frame and reproduces the thus stored data to output the data.
According to this invention having the feature as described above, when the user executes the data communication from the terminal by utilizing the data communication function of the cellular phone, the delivery side transmits, being mixed in the data exchanged in a unit of a frame, a message frame which is an error frame capable of correcting error and is irrelevant to the data communication by differing the CRC code by a particular operation such as bit inversion. The cellular phone detects the message frame, takes out the data contained in the message frame and stores the data, and displays the stored data as character information or picture information on the display screen. Or, the stored data are reproduced from a sound source as audio information. Thus, data such as advertisement can be delivered. That is, the data such as advertisement is delivered while the user executes the data communication. The message frame is simply an error frame when it is viewed from the normal data communication. When the data is received by a cellular phone to which this invention is not adapted, therefore, a request is issued for transmitting the data again. Namely, the delivery side transmits again the frame without data in response to the request for transmitting the message frame again, without affecting the data exchanged by the normal data communication.